New communication with Philae – commands executed successfully

The Philae lander communicated with the Rosetta orbiter again between 19:45 and 20:07 CEST on 9 July 2015 and transmitted measurement data from the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) instrument. Although the connection failed repeatedly after that, it remained completely stable for those 12 minutes. “This sign of life from Philae proves to us that at least one of the lander’s communication units remains operational and receives our commands,” said Koen Geurts, a member of the lander control team at DLR Cologne.

The mood had been mixed over the last few days; Philae had not communicated with the team in the DLR Lander Control Center (LCC) since 24 June 2015. After an initial test command to turn on the power to CONSERT on 5 July 2015, the lander did not respond. Philae’s team began to wonder if the lander had survived on Comet 67P/Churyumov-Gerasimenko.

“We never gave up on Philae and remained optimistic,” said Geurts. There was great excitement when Philae ‘reported in’ on 13 June 2015 after seven months of hibernation and sent data about its health. The lander was ready to perform its tasks, 300 million kilometres away from Earth.

However, Philae has to communicate with the ground stations through Rosetta, which acts as a radio relay. Restrictions on the orbiter’s approach to and orbit around the comet have not permitted regular communication with the lander. The data sent on 24 June did not suggest that the lander had experienced technical difficulties. Now, Philae’s internal temperature of zero degrees Celsius gives the team hope that the lander can charge its batteries; this would make scientific work possible regardless of the ‘time of day’ on the comet.

The received data is currently being evaluated. “We can already see that the CONSERT instrument was successfully activated by the command we sent on 9 July,” explained Geurts. Even now, Philae is causing the team some puzzlement: “We do not yet have an explanation for why the lander has communicated now, but not over the past few days.”

The trajectory of the orbiter, for example, has not changed over the last three weeks. However, one thing is certain; Philae has survived the harsh conditions on the comet and is responding to commands from the LCC team. “This is extremely good news for us,” said Geurts.

Can somebody set up a kickstarter project to make a “rosetta the movie” please? This missions has already had more tension than any blockbuster movie.

One question: Since the first contact on June 13th, is the lander only booting up when it gets direct sunshine, or are the batteries already charged to a certein degree? I thought the minimum operation temperature for the batteries were belwo 0°C.

So clearly Philae received and acted on the command to turn CONSERT on, presumably via the S band link? Or does CONSERT have an autonomous link – seems unlikely.

But this report is rather unclear about what the 12 minutes were; there is the 90MHz CONSERT transponder signal, but also CONSERT related telemetry which presumably goes on the S band link to Rosetta from Philae.
Would it be possible to clarify a bit exactly what link was active for the 12 minutes?

Everyone is holding their collective breath for a stable link, very best of luck to the team.

Thank you Emily for the details, as always. A lot of hope in my mind that Philae can continue communications without anomalies. Perhaps Philae is responding a little better now is because it has been ‘warmed up’ to 0 degrees Celsius for a long enough period of time. As said above, “Now, Philae’s internal temperature of zero degrees Celsius gives the team hope that the lander can charge its batteries; this would make scientific work possible regardless of the ‘time of day’ on the comet.” I still say though, that this mission has been SO outstanding, and it is just amazing to see the ESA doing such great things. I’m hoping that my own country’s NASA as well as the rest of the world’s space agencies can take some lessons from your examples of tenacity.

I’ve been quite worried about the status of Philae so this is at least some good news. One would have thought things would have been getting better and better with more sunlight and Rosetta in a better spot, but that’s not what’s happened. Hopefully they will figure out why contact is so sporadic.

The video updates are very nice to have though, a big thanks to DLR for them.

I’m asking your PR organizers and webmasters to please make more prominent the news from Philae. They might be bitter-sweet but the level of massive interest is more than you know. Once more: congratulations to all making this mission an enormous succes!

Is the identity of the transmitter unit in use, encoded in the message sent ? That would have made it easier to determine whether it was only one of the Tx units that still worked, and then to command only that unit to be used.
However for “safety” I think it’s still good policy to occasionally switch to the other Tx unit – in case the ‘working’ one fails, and the ‘dud’ one is just in a bad position.